This is a really good move. A lot of people have been offering Jupyter Notebooks along with their Books. This should bring down the effort in getting the book out. An important note though, R world has for something called 'bookdown' for quite sometime and many R developers have used it to write books. https://bookdown.org/

The only worry is that now a lot of data science enthusiasts are going to try to publish their Jupyter Notebooks collection as Kindle books!